Modern looms place increasing demands on the precision of components. This applies especially to the heddle shafts. They are operating at very high speeds during the weaving operation. It is absolutely necessary that heddle shafts are guided in a sufficiently precise manner to avoid added stress. However, it is an essential prerequisite that the heddle shafts themselves are manufactured in a sufficiently precise manner. Additionally, they must be constructed in such a way that the side struts may be simply disassembled for the insertion of heddles and re-assembled thereafter by having the original precision. Multiple changing of components in weaving mills has the consequence that shaft rods and side struts will be mixed up. Components being manufactured with higher precision solve this problem only to a small degree since larger differences from one production lot to the other is unavoidable. A novel constructional solution is thereby necessary. Corner edge connections from prior art do not, however, fulfill the requirements.
Various attempts are known from the prior art. Since it may be assumed that precise alignment of side struts was not the object of the proposed solution at the time of their creation, one must not be surprised that the precision reached up to now is not sufficient for current demands. According to that disclosed in Swiss patent 427 688 there cannot be achieved sufficient precision merely because of the tolerance or play which the bolt requires within the threads. As disclosed in U.S. Pat. No. 3,180,367 the bolts 22 shown therein would need to be dowel bolts fitted into correspondingly precise borings. However, such a solution is not achievable because of the stress that is currently placed on heddle shafts. The marginal portions 13 according to this prior art patent are either no longer in existence or they must not be weakened anymore by longitudinal borings. The invention disclosed in Japanese patent 56-39 478 has no elements that would make sufficiently precise alignment possible. The same applies for Japanese patent 56-14 3286 and Russian patent 105 143.
A solution for this problem is proposed in Japanese patent 37-31581. However, this is inapplicable for modern heddle shafts based on a completely different shaft profile in its design.
It is therefore an object of the present invention to propose a corner connection for a heddle shaft that assures simple and precise alignment of side struts and shaft rods in one place at all times, and which additionally fulfills present demands in total to which the heddle shafts are exposed. The invention allows the exchange of side struts and shaft rods with one another while nevertheless maintaining the necessary precision during assembly without extraordinary measures. The main objective is to achieve an alignment of the side struts and the shaft rods in one plane in a simple and repeatable manner.
A corner connection of a heddle shaft is provided according to the invention whereby on or in the shaft rod there is at least a first guide surface provided, which extends nearly parallel to the longitudinal axis of the shaft rod and which engages with a positive fit a second guide surface extending along a projection of the side strut at least nearly parallel to the shaft rod or perpendicular to the side strut.
The solution according to the invention has also the object to provide a corner connection which allows simple detachment of side struts and which always assures the same positioning precision of components during assembly. The positioning precision relates thereby to the twisting of components against one another and their alignment in one plane. Positioning is achieved according to the invention whereby guide surfaces are placed on the ends of the shaft rods and on each projection of the side strut, respectively, which ensures precise positioning as soon as said guide surfaces engage one another. The same precision in positioning is also achieved after detachment of the connection and reassembly of the components.
In a preferred embodiment, guide surfaces required for the side struts are placed directly on the projection of the side strut, which engages the shaft; whereby the guide elements, having the cooperating guide surface (s), are mounted or attached in or on the shaft rod by means of rivets, for example. The guide surfaces of the elements on the shaft rod are designed in the shape of ridges, whereas the ones on the counter-support are designed as grooves, for example. An exactly converse configuration is possible, of course, and it would not change the inventive effect. This effect is achieved in that the guide surfaces interlock with positive fit.
The projection of the side strut is inserted into the shaft rod to couple the shaft rod to the side strut. The guide surfaces of all components come thereby into contact with one another. The guide elements attached to the shaft rod may be drawn together by means of a tensioning bolt to secure the coupling whereby the side struts are held by clamping of their projections. A slot may be placed parallel to the longitudinal axis of the shaft rod and between the two guide elements to achieve the necessary flexibility on the shaft rod. In addition, one of the guide elements may be provided with threads for a tensioning bolt. The projection of the side strut may be provided with a cavity on the inside, extending parallel to the plane of the assembled shaft whereby the space of the cavity extending cross-wise to the plane is slightly larger than the diameter of the bolt. The depth of the cavity is sized in such a manner that the tensioning bolt may be rotated freely in the assembled condition of the side strut and shaft rod. This cavity, which is open toward the shaft rod, makes it possible to separate the side strut from the shaft rod while the tensioning bolt is slightly loosened so that the tensioning bolt does not have to be completely unscrewed from the threads and removed from the shaft rod. Loosening of the tensioning bolt is thereby prevented. Assembly of the side strut and shaft rod is possible in the same fashion. The bolt has to be rotated only slightly thereby.
Additional preferred embodiments of the corner connection defined in the invention are characterized in the dependent claims.